Friday, January 13, 2017

The Accidental Ichthyornis

Field identifications are problematic.

In mid October of this year the weather in Kansas was still warm enough to extend our dig season. That trip was pretty successful, finding a back half of a Protosphyraena and several small fish. Early on, Mike even thought he found another Pteranodon leg.

The drive to the site is a lot tougher when you can't see landmarks

We came out early in the morning. Man was it foggy. The entire day was supposed to be dedicated to finishing up excavation at several small sites. Since the "Pteranodon leg" site was so small, Mike and Jacob spearheaded the excavation there, while I wandered off to collect a Cimolichthys head and isolated Ichthyodectes site.

Several bones coming out at the site as discovered. Definitely not fish.

The "Pteranodon leg" showed some promising chunks of bone coming out, however inspection as they got down to the bone layer showed not a whole lot was there. Not like the large bones we were hoping to find for a Pterosaur.

That's a big hole for such a little block

Not a huge worry though, we perimeter the sites and very rarely expose the bone in the field, we will just find out what the "Pteranodon leg" looks like when we get back to the lab.

Jacob jackets and despairs as I tell him we have to go dig up another fish

Looking back at the video, just as Jacob began jacketing the specimen, I show up back at the site proudly announcing the discovery of the "Nia" Xiphactinus site that I blogged about last time. We all decided to drive over to the big fish and start work as the jacket cured. We were so stoked about the big fish that it was about a month later when we finally asked ourselves "Hey! Where did that jacket go?"

Turns out, we left it sitting there in the field, right next to a regularly visited oil well. Whoops! Over Christmas, Mike returned to the site to see if someone had poached it. Nope, the jacket was still exactly where we had left it. I guess you can say we got dang lucky. Let's never do that again.

Mike pulled it out and brought it back to the lab, where it sat for a week as I let it dry out (dry chalk behaves better than wet stuff when prepping, especially with small fossils). That's when the Eureka Moment happened: prepping down on the "Pteranodon leg" things weren't looking right. I immediately switched to my microscope, pin vise and very low pressure air abrasion (about 3psi with sodium bicarbonate blast media). My suspicions on the specimen's identity were confirmed when I found teeth. Pteranodon doesn't have teeth, but there's one small thing in the chalk with reptile-textured bone that does have it: a bird! Not only was it a bird, but the only complete articulated skull of Ichthyornis, who had been found only in fairly incomplete form since Marsh's days in the 1870s. This accidental and overlooked jacket suddenly turned into one of the rarest finds in the entire 160 year history of fossil hunting in the Niobrara.

You have to admit, what was exposed LOOKED like pterosaur bone. Since our techniques minimize exposure of bone in the field so that it can be prepared in a more controlled environment in the lab, we really had no idea that it was an Ichthyornis. I also found the Cimolichthys skull about 10 feet away as well as the Ichthyodectes across the ravine a day or two before Jacob and Anthony came out to join me on Monday afternoon. while only the skull (a spectacular find itself) has been revealed so far, the X-rays indicate a very high percentage of the body is also present, making it a true benchmark discovery!